Radio vacuum-tube circuits



May 1. 1928..

P. E. EDELMAN mm vAcumi TUBE CIRCUITS Filed June 5. 1922 lgN-VENTq Patented May 1, 1928.

UNITED STATES 3mm? E. album, or raw Yoax, 1v. Y.

name vacuum-roan cracorgrs'.

Application filed 111115 5,

The invention relates to a r-adioreceiving circuit in which substantially continuous oscillations may be obtained in the plate circult only without feeding backenergy to h the grid circuit as is customary in the prior art. A preferred embodiment of my present invention and examples of suitable modifications thereof are shown in, the accompanymg circuit diagrams of which- Y The "figure is a circuitof a receiving set.

- connected to an oscillatory circuit, it is custhroughout the view.

Similar numerals refer to similar portions In the prior art when a vacuum tube is l tomary to in some mannerfeed back a portion of the energy in the plate circuit to the rid circuit, such for example as shown in .S. Patent 1,113,149 dated October 6, 1914. The present invention is different therefrom 2" and may be used with either two, three or time. vember 7, 1905; 841,387, January 5, 1907, .and 879,532, February 18, .1908, suitable four element vacuum tubes such as are com nionly known in the radio art at the present- In U. S. Patents Nos. 803,684, No-

3 shown-in the accompanying drawings.

I have. set up such circuits and obtained very good results, there being a marked absence of undesirable regeneration and capacity effects such as are experienced when acircuit of the type shown in U. S. Patent No.. 1,113,149 above referred to is used.

Instead of, the usual feeding backof a portion of the energy of the plate circuit to the grid circuit, the gri'dcircuit indicated in the figure has a wire 11 connected to grid 12 and wire 11 connects to wire 10 and to =wires 14 and 15-of coil 16, while wire 10 also connects to c0115 and wire 4, so that the grid circuit is completed via coil 7, wire 4 8, wire 36, and filament 29 of vacuum tube 13. In accordance with this invention satis factory results are obtained as hereinafter set forth. The loudness and definition of the sounds heard in the receiver are remarkably .50 improved and noticeably free from distortion as is caused in the usual circuit of the prior art.

regenerator The present invention, contemplates improvements in the arrangement and conne'c-' tions of the apparatus,and to this end I have nicll fi d the usual circuit of the prior 1922. Serial in. 566,131.

art as shown in-the drawings and explained in the following description I depart from the customary arrangement 2 in such circuits and by referring for example to the figure, it will be noticed that an inductance coil 19 is connected in the plate circuit; coupled to this inductance coil is a short-circuited inductance coil 14; preferably both of these coils are constructed alike, and with a certain small distributed ca acity in the winding such that each coil as a broad range of natural periods of vibration. v

For'example, in the circuit tuned to 360 meters, I prefer touse'a coil of 90 turns of. v

No. 26 D. C. C. wire for the coil 19. These turns of wire are wound ina groove approxiinatel one-half inch deep and with an inside d aineter at bottonrof winding of three and a half inches. The. coil 16 is similarly wound on an insulating disk of the same dimensions and is short-circuited, by the wires 14, 15. The coil 16 must be closely coupled to the coil 19, the amount of coupling depending on the characteristics of the vacuum tube 13 in the circuit.- For most soft tubes the coupling should be very tight, but for a good sensitive tube a lesser coupling works best. The wires 14, 15 must be short-circuited otherwise when the wire 14 is open circuited, the circuit acts like a straight vacuum tube detector without amplifying effects.

In addition the wires '14 and 15 must be connected between the inductance 5 and the condenser 3.

It is to be understood that the plate C11- cuit coil 19 is not inductively coupled with either of the co ls 5 or 7 in the grid circuit.

The coils 16 and 19 are so designed as to be.

resonant to a broad band of frequencies.

Referring now to the figure, the usual single circuit receiving diagram is shown with tuning variometer; 5, and tuning condenser 3.. For 360 meters the variometer should have 40 turns on. each winding and the condenser 3, a capacity of .001 micro farad. The small 0011(161'156233 of .001

microfarad is not essential and may omitted as usually the wires 22, 26 afiord all the capacity necessary to by-pass the on some tubes in case the filament 29 is burned very bright, there will be a ght audible frequenc hum in the. receivers which, however, 1s not loud enough to interfere with the usual signal received. The

acquires amplifying and oscillatory properties without being coupled to the grid circuit.

In the circuit in the figure, a good condenserwith grid leak may be connected in series in the wire 10 without detriment to the behavior of this c rcuit, and in fact such a condenser with grid leak is advisable with certain makes ofvacuum tube 13. The, connection between short-circuited'coil 16 and the wire 10 may be omitted under: certain conditions with equally good results, but in general the circuit works best when the short-circuited coil 14 is connected as shown in the figure. J

Various changes andmodifications can be made by anyone skilled in this art within the spirit of this invention and within the scope of the appended claims, as I have shown by way of example a suitable embodiment as applied to a simple vacuum tube circuit and it will be readily understood that the invention is operative in other circuits such as, for instance, acircuit employing a plurality of vacuum tubes in :progressive or cascaded connection.

Inasmuch as the diagrams are self-explanatory in connection with the above description, it will be obvious that numerous changes may be made within the scope of the appended claims. i

What I claim is:

1. A vacuum tube radio system having an antenna circuit, a vacuum tube connected thereto, a radio frequency transformer connected with its primary winding in the plate circuit of said vacuum tube, with the secondary of said radio frequency transformer substantially short-circuited and connected by a single wire to said, antenna circuit.

2. A vacuum tuberadio system having a grid circuit containing a grid condenser and grid leak resistance, a plate circuit containmg in serles a direct current energy supply' and translating device, and a primary win ing of a radio frequency transformer constructed to have such distributed capacity in its winding as to make said winding natur-.

short-circuited through a low resistance, and

connected by a single wire to said grid circuit so as to afford a naturally resonant plate circuit which has oscillatory and amplifying properties without feed back coupling to said grid circuit.

,3. A radio receiving circuit including a three electrode vacuum tube having a grid circuit and a plate circuit, a radio frequency resonant inductance .coil in said plate circuit, a substantially short-circuited inductance coil coupled to said coil in said plate circuit, and a wire connecting such shortcircuited inductance to thegrid circuit to which said vacuum tube is connected.

4. In a radio circuit comprising a vacuum tube, a tuned input circuit, and an output .circuit therefor including an inductance,

means to control the amplifying action of said circuit, said means comprising a substantially short circuited coil connected to said input circuit and adapted to react on said inductance and comprise therewith an automatically varied esistance as the input circuit is tuned for-different frequencies.

5. In a radio circuit employmg a vacuum tube having a grid and a plate circuit, the

improvement which comprises an inductance comprising a plurality of turns of wire closely coupled thereto to serve as a regulator for the oscillatory currents in said plate circuit flowing thru said first inductance coil, said first inductance coil having a fixed relation with respect to said second coil, andsaidsecond coil having its terminal ends substantially short circuited whereby the reactance effect of said second coil is entirely' and automatically that due tothe second coil of itself according to the current flowing in said first inductance coil.

6. In a radio circuit including a three element vacuum tube, the improvement which comprises a plate coil in series with the plate of said vacuum tube, a substantially short circuited coil closely coupled to said plate coil and constructed to have capacity with respect to saidplate coil, and a connection from the grid of said vacuum tube to said short circuited coil whereby said capacity between said two coils'is shunted around said grid and said plate, to control the effective amplification of said vacuum tube.

In witness whereof, I havehereunto set my name this 27th day of May, 1922 at New York city, county and State of New York.

PHILIP E. ED'ELMAN.

.coil in said plate circuit with a second coil I 

